| 摘要 |
796,304. Moulding pipe ends prior to jointing. YOUTHED, S. E. Nov. 8, 1956 -[April 16, 1956], No. 11562/56. Class 87(2). [Also in Group XXVIII] Pipes, pipe fittings &c. made of thermoplastic synthetic resin material, e.g., polyethylene are joined by separately melting the inner annular surface on the end 2 of one pipe and the outer surface of a. spigot 1 on the end of the other pipe and then forcing the parts together, the outer wall of the socket being subjected to a radial compressive force, e.g., by a band 10, so as to press the parts together during cooling. Apparatus used, Fig. 1, comprises a steel tool 3 having a collar 4 which is chamfered at 6 to provide a lead for the spigot 1, and a plug 5 which fits in the socket 2, the ends having sizing lips 7, 7a respectively. Behind the lip 7 the collar is internally recessed at 8, the end of the recess being the same diameter as the lip 7, and then has a frusto-conical wall 9 which inwardly converges away from the collar mouth at 45 degrees. The external surface of the plug part is shaped similarly in a reverse manner, the recess 8a being followed by an outwardly converging wall 9a. To form the joint, the band 10 is fitted round the socket 2, the tool 3 is heated by a blow lamp &c. to a temperature between 350‹C. and 500‹C. and the socket 2 is applied to the plug 5 and pushed home until the rim reaches the stop 9a, and as it passes over the heated lip 7a the inner wall surface is melted, excess material in molten form scraped back so that the socket becomes accurately sized. The spigot 1 is then introduced into the collar 4 where similar melting and sizing takes place. The spigot and socket are left engaged for a pre-determined period, further heat being given by radiation from the recesses 8, 8a, and the pipe ends soften and take up the form shown in Fig. 2. They are then withdrawn, the lips 7, 7a serving to scrape the surfaces to remove oxidized material, and mated, the ring 10 exerting pressure on the joint until the heat dissipates. The stops 9, 9a serve to keep the unheated edges of the spigot and socket out of contact with the tool body during heating so as to avoid burrs and provide a smooth bore after mating, Fig. 4. In modifications the plug end of the tool is solid and in Fig. 5 (not shown), a heat retaining ring is applied to the outer wall of the collar. Fig. 6 (not shown) illustrates the use of a circular heating element over the heat retaining ring. The tool may be supported on a stand, and in further modifications has the collar and plug parts separately mounted and electrically heated. The sizing lips 7, 7a and the recessed radiant heat surfaces may be lined, e.g., with copper or phosphor bronze, and made detachable. |
